Time-of-flight sensors, as generally understood in the art, are used to determine a distance of an object from the sensor. Time-of-flight sensors operate by detecting light reflected off of a surface of the object where the light is emitted from a illuminator that is generally co-located with the sensor. Using the time-of-flight sensor, a processing device can determine the round-trip travel time of light emitted from the light source and reflected off of the object back to the sensor. With this information, and with the knowledge of the speed of light (constant c), the processing device can determine the distance of the object.
For any given physical area of a time-of-flight sensor, there is a fundamental tradeoff between optical sensitivity and image resolution. Smaller pixels generally provide a higher resolution by allowing more pixels in that given area than do larger pixels. However, larger pixels, by virtue of their increased area, are more sensitive to light (particularly, the light from the illuminator reflected off of the object of interest) and provide increased light detection and larger signal output as compared to smaller pixels.
Currently, a solution to providing adequate light detection using smaller pixels simply involves increasing the light illuminator output, thus providing for a higher intensity of reflected light to be detected by the pixels. Another solution involves limiting how small the pixels can be, which in turn limits the resolution of the image, or alternatively, requires a much larger physical area for the time-of-flight sensor. However, given the proliferation of mobile devices and other wireless or portable devices, a flexible solution combining lower light illuminator output power with higher resolution features with a smaller sensor footprint is desirable to conserve battery power and maximize performance while maintaining a usable sensor footprint, amongst other improvements.